<!DOCTYPE HTML>
<html>
<head>
<style>
#container {
  height: 500px;
  width: 500px;
  position: relative;
  overflow: hidden;
}
#panel {
  position:absolute;
  height: 100%;
  width: 100%;
  top: 0;
  left: 0;
  transform: translateX(0);
  background-color: yellow;
}
</style>
</head>
<body>
<div id="container">
  <div id="panel">
    <div style="width:300px; height:50px; background:blue;"></div>
  </div>
</div>
